The synthesis and processing of nuclear ribosomal RNA (rRNA) and heterogeneous RNA (hnRNA) will be studied in vivo in L1210 leukemia cells. (3H)Uridine and (3H)adenosine will be used to pulse-label and measure the synthesis of various species of nuclear RNA in L1210 cells. The methylation of rRNA and hnRNA, as well as the polyadenylation of hnRNA, will be examined as representative post-transcriptional processes. The nucleoside anticancer agents, cordycepin (3'-deoxyadenosine) and xylosyladenine, will be used to examine their specific inhibitory action on rRNA, poly(a), non-poly(A), non-poly(A)hnRNA and poly(A)hnRNA synthesis in the presence and absence of the adenosine deaminase inhibitor, 2'-deoxycoformycin. Analysis of high and low molecular weight nuclear RNA in the presence of either 5-azacytidine and dehydro-5-azacytidine or 5-fluorouracil will also be initiated.